Method of drawing door knobs



Feb. 28, 1961 C. C. HILLGREN METHOD OF DRAWING DOOR KNOBS Filed July 18, 1955 Jar/4. 62

4 Sheets-Sheet 2 CARL C. H/LLGREN, IN VEN TOR. Huebner, Beak/er, Worrel 6L Herzig.

A TTORNE Y5.

ULWL, QM

Feb. 28, 1961 c. c. HILLGREN 2,97 ,9

' METHOD OF DRAWING DOOR KNOBS Filed July 18, 1955 4 Sheets-Sheet 3 10; zqa 1a;

CARL C. H/LLGREN,

INVEN TOR. Huebner, Beeh/ Worre/ Herzig.

A TTORNEY5.

( i A QM METHOD on DRAWING. noon KNOBS Carl C. Hillgren, Newport Beach, Calif., assignor to Hillgren Manufacturing Company, Huntington Park, Califi, a corporation of California Filed July 18, 1955, Ser. No. 522,670

4 Claims. (Cl. 113-51) The application refers to the forming of bulbous articles from a pre-drawn blank by use of a combination involving a die cavity and hydraulic pressure. More particularly the invention relates to a technique for expanding a door knob blank into a finished door knob under circumstances wherein the die cavity is closed upon the blank, the blank being filled with a hydraulic liquid and sealed in the cavity whereupon one end of the blank is distorted by external pressure causing the hydraulic liquid to readjust itself and force the walls of the blank outwardly into contact with the inside surfaces of the die cavity.

Considerable attention has been given during relatively recent times to quick and inexpensive means of fabricating door knobs. Traditionally lock hardware has been made of brass and with relatively few exceptions emphasis has been placed upon manufacturing techniques intended to result in a sturdy product but without sufficient attention being given to the cost of producing the product. More recently certain innovations have been introduced into the industry which have attempted to make use of hydraulic expansion to produce the finished product. In some instances the hydraulic expansion has been the result of passing into the blank hydraulic liquid under considerable pressure to effect the expansion, the expansion being on some occasions somewhat unrestrained. On other occasions attempts have been made to produce hydraulic pressure by injecting a sealed plunger into the blank and simultaneously distorting the blank and ultimately closing the dies on the expanded blank to exert an external pressure so as to form the exterior of the blank. The technique required in the last mentioned process is somewhat involved and requires very careful preparation of the blank including sizing and polishing both the inside and outside of the open end in order to accomplish the expansion. Moreover the expansion has been sufficiently uncontrolled to result in many rejects wherein the blank has been burst before the dies have been permitted to close.

It is therefore among the objects of the invention to provide a new and improved method for reforming a hollow blank into a finished bulbous smooth-surfaced object by what may readily be defined as hydraulic distortion whereby the finished blank is quickly formed and the operation results in a substantially minimum number of rejects.

Another object of the invention is to provide a new and improved method of forming a hollow necked blank into a bulbous article in the shape of a door knob by employment of dies which close a die cavity before pressure is applied to the blank whereafter mechanical pressure is applied to the exterior of the blank causing the material to reform itself against the interior walls of the cavity uniformly in all directions as a result of hydraulic pressure built up by application of mechanical pressure to the exterior of the liquid-filled hollow blank.

Still another object of the invention is to provide a new and improved method for forming hollow necked ice blanks into bulbous articles in the form of finished door knobs whereby the hollow necked articles are fed by a new and improved continuous acting feeding mechanism by means of which one article at a time is enabled to be filled with hydraulic liquid, then placed between dies whereat it is released and the dies closed before the forming operation takes place.

Still another object of the invention is to provide in a mechanical-hydraulic die-forming method a new and improved positive-acting feeding step particularly well adapted to enable each blank adjacent the final stage to be filled with hydraulic fluid and thereafter fed with aswift smooth movement to the die operation whereupon the quantity of hydraulic liquid in the blank is slightly readjusted to full capacity immediately prior to the final combined mechanical hydraulic forming operation.

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter set forth,

pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a side elevational view of a sheet from which the hollow blank is drawn.

Figures 2, .3 and 4 illustrate successive drawing steps.

Figure 5 is illustrative of an optional annealing step.

Figures 6, 7, 8, 9 and 10 are side elevational views showing successive further drawing steps to accomplish a necking down of the open end of the blank.

Figure 11 is a vertical sectional view of the finished bulbous article in the form of a door knob.

Figure 12 is a vertical sectional view of a portion of the machine in which the blank is ultimately die formed showing the position of the blank in the die block just prior to the first step.

Figure 13 is a cross-sectional view on the line 13-13 of Figure 12.

Figure 14 is a vertical sectional view similar to Figure 12 showing the relative positions of the die blocks immediately prior to the expansion step.

Figure 15 is a vertical sectional view similar to Figure 12 showing the relative positions of the die blocks and working parts thereof at the completion of the expanding operation.

Figure 16 is a vertical sectional view of the upper die block and operating parts thereof illustrating a knock-out apparatus.

Figure 17 is a side elevational view of a portion of the machine illustrating the location and operation of a feeding device with respect to the die blocks.

Figure 18 is a cross-sectional view on the line 18-18 of Figure 17.

Figure 19 is a plan view of the feeding device at the first stage of the operation wherein one blank is to be fed to the die blocks.

Figure 20 is a horizontal sectional view of the feeding apparatus at the same stage of operation as Figure 19.

Figure 21 is a fragmentary vertical sectional view of the feeding apparatus at the stage of operation wherein a blank has been placed in position between the die blocks.

Figure 22 is a fragmentary plan view of the feeding apparatus showing the step immediately succeeding the step illustrated in Figure 21.

Figure 23 is a perspective view of a lifting cam associated with the feeding apparatus.

To understand and appreciate the apparatus and method herein disclosed steps illustrative of the formation of a hollow necked blank are illustrated by the line drawings of Figures 1 through 10, inclusive. In per forming the steps necessary in the production of the blank illustrated in Figure 10, substantially conventional apparatus and technique is employed such as that prevalent in brass drawing operations where shell casings are made and where on occasion blanks have been formed for the production of door knobs. Ordinarily a fiat sheet 2 of brass is fed in strip form through suitable conventional machinery wherein by employment of successive drawing operations the blank is formed first into a wide shallow cup 3 which is then elongated successively into the form of cups 3a and 3b. Should the brass sheet material or other sheet material chosen be of such thickness or of such character as will respond to an annealing operation, an electric coil 4 may be so formed that the blank 3b is passed through it and there subjected to an annealing operation.

Following the formation of an elongated cup such as that illustrated in Figure 4, the cup is necked down at the open end. To accomplish this the cup 31) is passed through a series of drawing dies of substantially conventional construction which results in the successive formation of hollow necked blanks 5, 5a, 5b, 5c, and 5d, as illustrated respectively in Figures 6 through 10, inclusive. It will be noted with respect to the last identified figures that the lower portion of the blank remains at substantially the same outside diameter as the elongated cup 31) but that a neck 6, as illustrated in Figure 10, is finally formed having an exterior diameter substantially the same as the exterior diameter of the ultimately formed bulbous article or door knob 7, illustrated in Figure 11. The neck 6 is considerably smaller than a neck 8 which is formed on the blank 5, namely, the first formed blank of the successive necking operation.

It will be noted that the apparatus and the method or process herein constituting applicants invention is one directed to a reforming of the hollow necked blank 5d of Figure 10 which is presented to the process and apparatus for further working. An incident in the correct forming of the ultimate bulbous article or door knob lies in providing the blank 5d with a cylindrical lower portion, which may for convenience be termed the blank, which has a much smaller diameter than the ultimately formed bulbous portion of the final product but which, on the other hand, is very considerably longer than the finally formed bulbous portion. It has been found that if a door knob, for example, is to have a wall thickness at the portion of greatest diameter sufficient to serve expectations, extra metal must be provided in the blank which will avoid over thinning out during the stretching operation. It being impractical to provide the excess amount of metal by increasing the diameter of the lower blank portion 5d, the extra metal is provided by increasing its length. The neck 6 is preferably, however, drawn down to about its final shape and size during the conventional drawing and necking down operation so that no further operations are needed with respect to the necked portion except perhaps a slight reforming of the curved area of junction of the neck with the blank portion. Inasmuch as the expanding step is one which should be made rapidly and in a single operation, certain precautions need be taken to assure a minimum of rejects, to

assure a full expansion of the blank within the die cavities, and to be sure of a proper confinement of a desired amount of hydraulic liquid to the end that when exterior pressure is applied to the blank it will produce the desired expansion without marring the exterior surface of the finally finished blank.

The invention includes an apparatus adapted for operation with a conventional press of suitable capacity, portions of which are illustrated in Figure 17 taken with details of the mechanism illustrated in Figures 19 through 23 and details of the die block apparatus illustrated in Figures 12 through 16, inclusive. p Generally speaking the press includes a bed 10 designed to support colums 11 and 12.

' A composite shaft 13 is supported upon bearings 14 and 15.

Inasmuch as the press as already referred to is of substantially conventional design, details of press construction have been omitted except to the extent of there being illustrated a crank housing 16 on the composite shaft from which a piston (not shown) extends downwardly into engagement with a reciprocating head 18' to which an upper platen 19 is attached. The reciprocating head is adapted to be contained in ways 20 and 21 to guide the reciprocating operation of the head in a proper path. in the upper platen 19 is a die block 22 adapted to cooperate with a lower die block 23 supported upon a bass 24 on the bed It). In the presently disclosed embodiment of the invention the lower die block 23 is essentially the stationary die block and the upper die block 22 is the moving die block. Some limited motion for a specific purpose is, however, present in the lower die block.

As illustrated more particularly in Figures 12, 14 and 15, the lower die block 22 reciprocates vertically in a bore 25. Compression springs 26 are normally biased to elevate the lower die block to the uppermost position illustrated in Figure 12. To limit movement of the die block upwardly, screws 27 extend slidably through the die block and into the base to a position where heads 28 of the screws engage the bottom of suitable recesses 28 when the die block is shifted by the spring 26 to uppermost position. A ring 29 fits in the bottom of the bore 25 and is provided with a central cylindrical opening 30 for reception of a plunger 51. A spring 32 of less strength than the spring 26 is located at the bottom of the opening 30 and normally urges the plunger upwardly to the position illustrated in Figure 12. To hold the plunger in proper position there is provided a screw 33 extending upwardly through the bottom of the base 24 into threaded engagement with the plunger. A head 34 on the screw reciprocating in a pocket 35 limits movement of the plunger upwardly to the position shown in Figure 12.

It is important to note that the die block 23 is provided with a die cavity 4-0 which forms the outer portion of the finished article. At the bottom of the die cavity 40 is a large central opening 41 communicating with a bore 42 which contains the plunger 31, and in which the plunger is free to reciprocate with a snug sliding fit. The plunger is provided with an upper concave face 43 and in specific positions the concave face forms a portion of the interior Wall of the lower die cavity.

In order to protect operation of the plunger 31 and particularly the screw 33 a plug 44 is inserted into the lower end of the pocket 35 to seal off the interior of the pocket.

The upper die block 22 is provided with an upper die cavity 47 formed to the shape of the portion of the door knob adjacent a sleeve section 48. At the center of the upper die cavity 47 is a recess 49 which extends upwardly and is adapted to receive the sleeve section 48 in a snug fit. Within the recess is a piston 50 having an annular recess 51 in which is positioned an Q-ring 52 by means of which the piston is given a snug sliding fit in the recess 4?. A projection 5% much smaller in diameter than the piston extends below the piston. The piston 50 serves as a knock-out member and for this purpose the piston is provided with a piston rod 53 shown to good advantage in Figures 14, 15 and 16. The piston rod- 53 extends upwardly through a hydraulic jacket 54 which provides a cylindrical chamber 55. The chamber is divided into upper and lower sections by means of another piston 56 which is similarly provided with annular recesses 57 in which O-rings 58 are located. A spring 59 tends normally to urge the piston 56 upwardly. The piston may be secured to the piston rod 53 by means of a screw 60, as shown in Figure 14.

In the upper platen is a hydraulic passage 61 to which access is had by a fitting 62. Hydraulic fluid entering under pressure into the passage 61 is adapted to move the piston 56 downwardly which in turn moves the piston rod 53 and piston 50 downwardly through a knock-out stroke. To assist the spring 59 in returning the piston 56 to initial position, a hydraulic passage 63 is adapted to admit hydraulic fluid to the underside of the piston 56 at appropriate intervals and to exhaust hydraulic fluid therefrom on alternate phases of the cycle of operation.

In order to have the device operate properly, an effective feed mechanism need be provided. In the chosen embodiment of the invention the feed mechanism consists of a track or trough 70 to which the blanks are advanced by a belt conveyor 71. The blanks which are being advanced are the blanks 5d of Figure 10. Guides 72 are spaced one from another forming a channel therebetween just wide enough to permitfree movement of the blanks. Constant feed means of a conventional sort is employed to operate the belt conveyor 71. An elongated land 73 supports the last five or six blanks around which they are guided continuously by the guides 72. A hydraulic supply line 74 is located near the mid-portion of the land for supplying hydraulic liquid to the hollow blanks. Immediately adjacent the right-hand end of the land 73, as viewed in Figure 21, is an elevator platform 75 just long enough to receive the last blank in line. Details of the construction of the platform 75 are illustrated in Figure 23. As there shown a central level portion 76 is the part upon which the blank actually rests. Legs 77 and 78 are attached to the ends of the level portion, these legs being somewhat greater in length than the diameter of the blanks and positioned spaced from the last two or three blanks in line so that the blanks slide between the legs. A spring 79 acts normally to urge the platform in an upward direction guided by posts 80.

When the platform is to receive a blank it must be down in the position illustrated in Figure 21. So as to be pressed into that position, cam faces 81 and 82 are provided against which acamway 83 is adapted to press at a certain stage of operation of the feeding mechanism. The camway is carried upon a base 84 of a carriage 85, the carriage being mounted for side to side reciprocation confined within tracks 86. The tracks are supported by upright elements 87 on the bed 10.

The carriage is reciprocated by action of a cam wheel 90 having a cam track 91 therein within which a cam follower 92 is adapted to slide. The shape and configuration of the camway is made to cooperate with rotation of the composite shaft 13 so that the carriage will be reciprocated at proper intervals. The cam 92 is attached to the end of a rocker 93 pivotally supported by a bolt 94 in an adjustable plate 95 attached to a stationary arm 96. The rocker has a slot 97 within which is a bolt 98, the bolt in turn being mounted in a head 99 to which a shaft 100 is attached. Surrounding the shaft 100 is a spring 101 which acts at one end against a collar 102 and at the other end against an abutment 103. The collar in turn is adapted to bottom against another abutment 104.

Also mounted upon the carriage 85 are a pair of arms 107 and 108. These arms are pivotally secured to the carriage by bolts 109 and 110. Fingers 111 and 112 on the arms 107 and 108, respectively, contain curved faces 113 shaped to encompass the last blank in line. The arms as illustrated in Figure 21 have each a horizontal portion 114 and a downwardly extending vertical portion 115. The fingers are attached to the lower ends of the vertical portion 115 in each case. To steady the blank while it is being grasped and moved by the arms there is provided a Y-shaped extension 116 which is attached to and moves with the carriage 85.

Normally the spring 117 tends to pull the arms 107 and 108 together as illustrated in Figure 19. At the initiation of a stroke of the carriage it is withdrawn to the position of Figure 19. In that position the platform 75 is in an upward position wherein it has lifted a blank to position where it can be grasped by the fingers 111 and 112. As the carriage advances from left to right, as viewed in Figures 19 through 22, inclusive, the fingers move the blank to the position illustrated in Figure 21. The mechanism and timing is such that the blank is centered between the die blocks. The platform it will be understood has been elevated to a position wherein the bottom of the blank is level with an upper face 118 of the lower die block. The blank is thus slid easily into place. Sliding is accomplished by reciprocation of the shaft which in the first instance acting through the spring 101 moves the carriage from left to right. Inasmuch as the fingers are mounted on the carriage, the fingers also with a blank between them are moved from a left position which is the location of the last blank in line to a right position which is centered between the die blocks.

As the shaft 100 continues to be moved from left to right, the base 84 moves from left to right through a distance such that the camway 83 presses against the cam faces 81 and 82 causing the platform 75 to be moved downwardly against pressure of the spring 79 to a position where it can again accept the last blank in line. As the carriage continues to move, the abutment 104 and wings 119 and 120 thereof abut against the tracks 86 and halt further motion of the carriage toward the right. Since the shaft 100 continues to be pressed in a direction from left to right, the spring 101 will compress and the end of the shaft 100 will press against cam faces 121 and 122 on the arms 107 and 108, respectively, causing the arms to move outwardly away from contact of the fingers with the blank. Movement will be such that the fingers entirely clear the faces of the die blocks.

Having released the blank in position between the die blocks, action of the camway 91 and cam 92 will retract the carriage far enough to clear the Y-shaped extension before the dies meet.

As previously noted the blanks are filled with hydraulic liquid from the hydraulic supply pipe 74 as they approach the position last in line. The amount of hydraulic liquid need not be metered so long as a sufficient quantity is injected into the hollow blank to bring the level near the top. The movement of the blank as it is fed to position between the die blocks may spill some of the fluid but any quantity which might be spilled is compensated for when the upper die block 22 is lowered. As the upper die block is so-moved, the projection 50' displaces a sufficient amount of hydraulic liquid to bring the level of the liquid to the top rim of the sleeve section 48. At the same time the piston 50 is lowered into engagement with the rim of the sleeve section. These parts are so positioned that the upper die block moves downwardly until the sleeve section 48 is received within the recess 49 and forms a suificient seal around the exterior of the sleeve section.

As the upper die block continues to descend, the bottom of the blank will be brought against the concave face 43 of the plunger 31. This will force the plunger downwardly against tension of the spring 32 until the plunger bottoms against the base 24. This will be the position illustrated in Figure 14. At this point the face 118 of the lower die block will receive a face 123 of the upper die block and the die cavity formed by the respective die cavities 40 and 47 will be sealed and closed.

Thereafter as the upper die block continues to descend, it forces the lower die block downwardly against tension in the springs 26. Meanwhile the plunger 31 remains stationary and the effect is that of relative movement of the plunger into the lower die cavity while pressing against the bottom of the blank. Inasmuch as the hydraulic liquid is sealed Within the blank, the liquid will be displaced outwardly forcing the wall of the blank outwardly until it fills the interior of the die cavity. The final position will be that illustrated in Figure 15. Thus, although no pressure 'is exerted by impressing the plunger against the bottom of the blank and under the chosen circumstances wherein the volume of the hydraulic liquid is substantially the same as the volume of the combined die cavities, the blank will be forced into engagement with the interior of the die cavities and a smooth, substantially finished knob will be the result.

As the composite shaft continues to rotate through the cycle just described, the upper die block 22 will recede upwardly and at the same time hydraulic liquid under pressure will be injected into the hydraulic passage 61 forcing the piston 56 downwardly and hence the piston rod 53 and piston 50 downwardly so as to eject the finished knob. When the finished knob falls upon the lower die block, feeding of the next blank into place will push the knob off the die block so as to roll it down an exit chute 125. At this point the cycle begins to repeat in order to advance the next blank to position between the dies where it will be formed in the manner just described.

There has accordingly been described herein a simple and eifective combined feeding method and die forming method for making door knobs from an expanded necked blank, the method being relatively simple in its operation and being simple and effective so as to produce dependable expanded products with a minimum of rejects. Expansion into a closed cavity in the manner described is productive of the dependable product of the system.

While I have herein shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent methods.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

l. A process for converting a substantially cylindrical blank of predetermined interior-volume and having a neck of diameter smaller than the rest of the blank into a completed bulbous smooth-surfaced object having a straight cylindrical neck comprising forming upper and lower die blocks into upper and lower die matching cavities and forming a neck recess and a central opening therefor at the center of the upper cavity and making the aggregate volume of the cavities substantially the equivalent of the volume of said blank, forming an extra blank bore centrally with respect to and below the lower die cavity with an available volume temporarily occupied by a'lower portion of the blank at least equal to the difference in volume between said aggregate volume and that portion of the volume of the blank which lies within the die cavities when said lower portion of the blank is temporarily within the blank bore, substantially filling said blank with hydraulic liquid, inserting a plunger having a small object at the lower end through said central opening loosely into the neck of the blank and displacing liquid in the blank whereby to remove the air present in and adjacent the interior of the blank and to bring the hydraulic liquid to a predetermined level, sealing said central opening exterior with respect to the blank, placing the recess around the neck of the blank and sealing the blank at the base of the neck on the exterior with the wall of the upper die cavity and sealing the liquid entirely within the blank, moving said die blocks into face to face relationship and extending said blank into said here, then exerting pressure endwise against the bottom end of the blank and pushing the blank out of the bore and displacing hydraulic liquid against the wall of the blank and forcing the wall of the blank into contact with the inside of said die cavities, then opening said die cavities and pressing downwardly against the rim of the neck expelling the blank in finished altered form downwardly from the upper die cavity.

2. A process for converting a blank of predetermined interior volume having a substantially cylindrical smooth walled bulbous portion forming a closed end and a substantially cylindrical smooth walled neck portion of smaller uniform diameter throughout the length thereof forming an open end, said neck portion being joined'to the bulbous portion by an annular curved section into an annular curved bulbous object having a neck with a smooth walled interior of predetermined diameter comprising forming upper and lower vertically separating die blocks into upper and lower matching die cavities each adapted to form a partial section of the bulbous portion respectively above and below a horizontal parting line, forming a die cavity in the upper die block for the neck and a central opening therefor at the center of the upper die cavity and making the aggregate volume of the die cavities substantially the equivalent of the volume of the blank, placing a quantity of hydraulic liquid in the blank roughly equivalent to the aggregate volume of the die cavities, displacing liquid in the blank by insertion of a block loosely within the die cavity for the neck until the liquid level is even with the rim of the neck, closing off the interior of the blank at said rim, and forming a single annular seal between the upper die cavity and the exterior only of the blank, whereby to prevent egress of said liquid during a subsequent forming operation, moving said die blocks into face to face relationship at said horizontal parting line, then while the die blocks are in face to face relationship exerting endwise pressure against the exterior of the blank at the closed end thereof moving said end inwardly toward the cavities and forcing the wall of the blank into contact with the inner surfaces of the die cavities, then opening the die cavities along said horizontal parting line and expelling the finished object downwardly from the upper die cavity.

3. A process for converting a blank of predetermined interior volume having a substantially cylindrical smooth walled bulbous portion and a substantially cylindrical smooth walled neck portion of smaller uniform diameter throughout the length thereof joined to the bulbous portion by an annular curved section into an annular curved bulbous object having a neck with a smooth walled interior of predetermined diameter comprising forming upper and lower vertically separating die blocks into upper and lower matching die cavities each adapted to form a partial section of the bulbous portion respectively above and below a horizontal parting line, form-ing a die cavity in the upper die block for the neck and a central opening therefor at the center of the upper die cavity and making the aggregate volume of the die cavities substantially the equivalent of the volume of the blank, forming an extra blank bore centrally with respect to and below the lower die cavity with an available volume temporarily occupied by a lower portion of the blank at least equal to the difierence in volume between said aggregate volume and'that portion of the volume of the blank which lies within the die cavities when said lower portion of the blank is temporarily within the blank bore, placing a quantity of hydraulic liquid in the blank roughly equivalent to the volume of the blank, displacing liquid in the blank by insertion of a block loosely within the die cavity for the neck until the liquid level is even with the rim of the neck, closing off the interior of the blank at said rim and forming a single annular seal between the upper die cavity and the exterior only of the blank whereby to prevent egress of said liquid during a subsequent forming operation, moving said die blocks into face to face relations-hip at said horizontal parting lineand extending a closed end of said blank into said bore, then exerting endwise pressure against the closed end of the blank pushing the lower portion of the blank into the space formed by the upper and lower die cavities and forcing the wall of the blank into contact with the inner surfaces of the die cavities, then opening the die cavities along said horizontal parting line and expelling the finished object downwardly from the upper die cavity.

4. A process for converting a substantially cylindrical blank of predetermined interior volume and having a neck of diameter smaller than the rest of the blank into a completed bulbous smooth-surfaced object having a straight cylindrical neck comprising forming upper and lower die blocks into upper and lower die matching cavities and forming a neck die recess and a central opening therefor at the center of the upper cavity and making the aggregate die cavity volume substantially the equivalent of the volume of said blank, forming an extra blank bore centrally with respect to and below the lower die cavity with available volume temporarily occupied by a lower portion of the blank at least equal to the difierence in volume between said aggregate die cavity volume and that portion of the volume of the blank which lies within the die cavities when said lower portion of the blank is temporarily within the blank bore, inserting a plunger having a small object at the lower end through said central opening loosely into the neck of the blank and displacing liquid in the blank whereby to bring the liquid level even with the rim of the neck, placing the recess around the neck of the blank and sealing the blank at the base of the neck on its exterior with the wall of the upper die cavity and sealing the liquid entirely within the blank,

moving said die blocks into face to face relationship and extending said blank into said bore, then exerting pressure endwise against the bottom end of the blank and pushing the blank out of the bore and displacing hydraulic liquid against the wall of the blank and forcing the wall of the blank into contact with the inside of said die cavities, then opening said die cavities and pressing downwardly against the rim of the neck whereby to expel the blank in finished altered form downwardly from the upper die cavity.

References Cited in the file of this patent UNITED STATES PATENTS 795,020 Bart-helmes July 18, 1905 1,766,098 Booth June 24, 1930 2,210,437 Wendel Aug. 6, 1940 2,407,855 Stephens Sept. 17, 1946 2,493,053 Zatyko Jan. 3, 1950 2,592,867 Cuq Apr. 15, 1952 2,688,297 Livermont et a1 Sept. 7, 1954 FOREIGN PATENTS 9,889 Great Britain of 1900 

